Description The Labrador Sulphur (Colias nastes) is a butterfly in the Pieridae family. In Europe, it is found in the North of Norway and Sweden and on rare occasions in Northern Finland. It is also found in North America, specifically in Alaska, Canada, and the Rocky Mountains, Washington, Montana and on Greenland. In Asia, it is found in the Altai Mountains, the border regions of Russia, China, Mongolia, Kazachstan, the Sayan mountains, the North of Siberia, and in the Chukotka Autonomous Okrug.

The wingspan is 31–45 mm. The butterfly flies in May to August depending on the location.

The larvae feed on Astragalus species, especially Astragalus alpinus and Astragalus frigidus. In North America it is also recorded on Trifolium repens and possibly Vaccinium species.